Mark bit his lip and stared at her. "I'd... I'd like it if you were more like me."
Eve's eyes brightened. "Oh, of course! You're the best brother in the whole world, I would love to be more like you!" Her eyes sparkled. "It'd be like a dream come true!"
"Okay, but when I mean 'like me', I mean I want you to be my identical twin. That means becoming male and everything else," he warned. "Are you okay with that?"
"Yes, yes, a thousand times yes!" Eve squealed. Mark blinked at her, then shrugged. Well, if she was okay with it...
He clicked on her profile once more, input the changes, then applied and waited as she transformed once more.
The first thing that Mark noticed was his mind changing. It was getting harder and harder for him to think of her as 'Eve' and as his sister. He'd made reality alter to fit the narrative he wanted, and it seemed that those replacement memories were being pushed to the forefront of his mind, swallowing up what he knew was real. Thoughts started to filter in, about growing up with his twin, Evan. Mark looked at him, still in a (mostly) feminine body and called out his name. "Evan?"
He responded immediately. "Yeah, bro?" His voice, too, was still that of a girl, but was quickly deepening as he kept on speaking, Adam's apple growing in slowly. "Woah. It's so weird. I know that I was Eve, but all I can think about is being Evan, and being a man. It's crazy!"
"Yeah, I know." Mark eyed his brother as his face began to change. His jaw grew more stocky and square, his eyes lightened from dark green to the lighter tone mirrored in his brother. His hair darkened from blond to brown. Down below, his shoulders broadened, his waist narrowed, and his breasts simply melted away, leaving a broad, flat chest as if they'd never been there in the first place.
Soon, the transformation paused for a minute as Mark stared at the almost perfect copy of himself. Save for the cock and monumental height, Evan was identical. "Bro, I'm just like you now!" Evan said, smiling. Then, his body gave a lurch.
While he kept many of the same features as Mark, his body wasn't done changing. His jawline sharpened, his skin cleared. His eyes formed into a permanent smolder, his hair sculpting itself into a well-groomed, fashionable hairstyle that only served to enhance his beauty. Soon, Mark was staring down a version of himself with what looked like some sort of beauty filter over the top. Except, there was no filter. This was real.
Evan's Adam's apple expanded further as his voice became a rich, bassy rumble. "Ohh, Mark, what did you do to me?" he asked, as his whole body began to expand. Not upward, at least, but outward. Muscles began to pile over his limbs, bulking him up until what tattered scraps of cloth remained to cover his body tore away completely, revealing his stunning physique for all to see. His pecs were like a shelf, jutting straight out from his chest. His abs were the size of bricks, each one stacked perfectly atop the other, with almost an inch-deep cavity between the excessively defined muscles. His back was like a mountain range, his legs like thick tree trunks, his arms inflating to the size of footballs with steel cable veins crisscrossing.
Finally, his cock surged another six inches, while his balls became the size of cantaloupes. Evan panted as the transformation suddenly let go of him. "What..." he asked again, as he caught his breath. "What did you do to me?"
Mark shivered at his voice. Even panting, Evan's voice was smooth as butter and sultry enough he could probably make you cum without even laying a finger on you. "I made you like me," Mark replied. "But better."
"Better?" Evan echoed.
"More handsome. Stronger. Smarter. Far more virile."
"I can see that," he chuckled, patting his crotch to emphasize just how large he was down there. "But why? Don't get me wrong, it feels amazing, and I'm happy with anything that you're happy with, but why?"
"I mean, you're basically living my fantasy right now," Mark said.
"Am I?"
"And, I don't know, it's really hot to see you like this!" He gestured to all of Evan's body - his muscles, his cock, his drop-dead gorgeous face. "I mean, you're the perfect guy!"
"I guess so," Evan agreed. "Wait, did you say smarter as well?"
"Yeah. Why not? I upped your IQ by a good few points."
"How many?"
Mark chewed on his lip thoughtfully. "Let's see. I edited you up from my IQ, which is 110. So, I think I put it up to like, 150 or something."
Evan stared. "You have no idea how high that is, do you?"
"Not really, no."
"And that doesn't bother you?"
"Again, not really," Mark replied. Evan's piercing green eyes studied him, newfound intelligence glittering in their depths.
"Okay," he said finally. "I mean, I'm happy about anything you do to me. My only wants are to serve you. But I'm beginning to get an idea of what you're truly wanting, Mark. If I may speak freely, I think your deepest desire is..."